Heating on the planetary scale

by Paul Kando

Readers of these weekly columns know how heat, air and moisture interact in a heated house. The same physics apply on a planetary scale: When heated, water evaporates, absorbing its heat of evaporation. Heated air expands, becomes lighter and rises, replaced by cooler air, creating a convective loop. Warmer air holds more water vapor, so when it cools the moisture it holds precipitates. The big difference is the heat source: The Earth uses no furnace; solar rays combine with the ability of Earth’s atmosphere to trap heat to provide conditions favorable to life. Without the greenhouse effect Earth would be an inhospitable 30 degrees colder.

For thousands of years the atmosphere contained just the right amount of greenhouse gases — mostly carbon dioxide (CO2) and methane (CH4) — to maintain a global temperature optimal for living things to thrive. But, like a house with the boiler running on a hot day in July, Earth can overheat. This is what has been happening due to human activities over the last two centuries. Burning fossil fuels has increased the atmospheric CO2 level by more than one-third since the beginning of the industrial era, reaching its highest level in 650,000 years. The feed-lots of industrial meat production have increased CH4 levels. Nitrous oxide (NOX) and halocarbons — byproducts of industrial processes — are also potent greenhouse gases. Add deforestation — removing trees, nature’s tools to balance the carbon cycle — and the consequence is an overheating planet under distress.

Eleven of the 12 years between 1995 and 2006 have been the warmest on record, kept since 1850. Global air and ocean temperatures have been steadily increasing. Glaciers and snow cover have declined, with their melt-water contributing to sea-level rise. Melting land-based ice in Greenland and Antarctica will contribute still more. And, of course, as the ocean warms it expands, compounding the rise.

Due to increased evaporation, there were more intense and longer droughts observed since the 1970s, especially in and near the tropics. The frequency of heavy precipitation over most land areas has also increased — what goes up must come down. If greenhouse-gas emissions are not significantly reduced, the availability of fresh water around the globe is likely to change, with some areas becoming wetter, some drier. Drought and flooding will increase. Fresh water stored in glaciers will decline, jeopardizing water supplies for over a billion people.

Greenhouse-gas emissions damage the ecosystem as well. Twenty to thirty percent of the Earth’s plants and animals face extinction. As oceans dissolve CO2, carbonic acid forms. It interferes with the formation of shells, affecting sea life from kril to lobster and ultimately the whole aquatic food chain.

The polar regions are warming at twice the rate of the rest of the globe. By 2080, due to polar ice melt, sea levels are likely to be 4 to 6 meters higher than today. Researchers predict that annual flooding, due to sea-level rise and increased storm intensity, will displace millions of people around the globe. Climate-related interference with food production could lead to malnutrition and scores of consequent disorders. Heat waves, floods, storms, drought and wild fires will cause premature deaths. Higher climate-related ozone levels are likely to contribute to cardiovascular diseases. Infectious disease vectors, like ticks and mosquitoes, will continue to spread to regions formerly too cool for them to survive the winter. Maine is already infested with ticks, with over 1,000 cases of Lyme disease reported over the last two years.

Formerly warm-climate pests spreading to once cooler climates decimate species with no natural defenses against them. Millions of acres of pine and spruce forest have already fallen prey to the pine bark beetle in the Northwestern United States and Canada. In turn, dead forests are fodder for wild fires of the sort we are witnessing this week in Colorado and New Mexico. Maple and birch forests in New England may disappear due to the warming climate.

Such changes may not be as gradual as had been thought earlier, due to such positive-feedback effects as the release of large amounts of CH4 stored in frozen methane hydrates in the Arctic. According to the International Energy Agency, global CO2 emissions climbed 22 percent between 1980 and 2000. Since 2000 the rate has tripled over the 1990-99 average. By 2030 “business as usual” is likely to result in an increase of 55 percent over 2004 levels.

Some permanent climate change is probably unavoidable but there is still a solution: We can stop overheating the planet. The current economic model is not cast in stone. Our whole economic system — based as it is on fossil fuels as the prime energy source and wasteful consumption of unnecessary “stuff” — can be re-thought. The good news is that a more sustainable economy means a happier planet as well, if not for seniors like myself, then for our children and grandchildren.